{ INFORMATICS.MCCME.RU
  Problem statement: http://informatics.mccme.ru/moodle/mod/statements/view3.php?chapterid=295
  Verdict: Accepted
}
uses SysUtils, Math;
 
var
	a,b,c:int64;
 
begin
reset(input,'input.txt');
rewrite(output,'output.txt');
read(a,b,c);
if (a+b>c) and (a+c>b) and (b+c>a) then write('YES') else write('NO');
end.
 